Poros
From Tolkien Gateway
The river Poros was a river in south of Gondor.
It formed the northern border of the contested land of Harondor, South Gondor, and the southern border of Ithilien. During the later Third Age it was the effective southern border of Gondor.
About 400 Númenórean miles long, it began in the Ephel Dúath of Mordor and then flowed sout-west for about 300 miles, when it bent north and met the Anduin just before the Anduin began its delta.
The Poros was crossed by the Harad Road at the Haudh in Gwanûr.
